1. Field of the Invention
The present invention relates to a position detecting method for a touchscreen panel, a touchscreen panel, and an electronic apparatus.
2. Description of the Related Art
The touchscreen panel is an input device that allows direct inputs to a display. The touchscreen panel is provided and used on the front surface of the display. The touchscreen panel, which allows direct inputs based on visually acquired information on the display, has been widely used for various purposes.
Of touchscreen panels, those using resistive films are well known. In touchscreen panels of the resistive-film type, an upper electrode substrate and a lower electrode substrate are provided so that their respective transparent conductive films face each other, so as to allow the transparent conductive films to come into contact with each other in response to an application of force to a point on the upper electrode substrate. As a result, it is possible to detect the position of the point to which force has been applied.
Touchscreen panels of the resistive-film type may be divided roughly into a four-wire type and a five-wire type. The four-wire type of touch panel has X-axis electrodes provided on one of the upper electrode substrate and the lower electrode substrate and Y-axis electrodes provided on the other one of the upper electrode substrate and the lower electrode substrate.
On the other hand, the five-wire type of touchscreen panel has both the X-axis and the Y-axis electrodes provided on the lower electrode substrate, and has the upper electrode substrate serve as a probe for detecting voltage. (See, for example, Japanese Laid-Open Patent Application No. 2004-272722 and Japanese Laid-Open Patent Application No. 2008-293129.)
By way of example, a description is given, with reference to FIG. 1 and FIG. 2, of a five-wire type of touchscreen panel. FIG. 1 is a perspective view of a five-wire type of touchscreen panel. FIG. 2 is a schematic cross-sectional view of the five-wire type of touchscreen panel.
Referring to FIG. 1 and FIG. 2, a five-wire type of touchscreen panel 200 (hereinafter, “touchscreen panel 200”) includes a film 210 and a glass 220. The film 210 has a transparent conductive film 230 formed on its one side and serves as an upper electrode substrate. The glass 220 has a transparent conductive film 240 formed on its one side and serves as a lower electrode substrate. The film 210 and the glass 220 are provided so that the transparent conductive film 230 and the transparent conductive film 240 face each other across a spacer 250. The touchscreen panel 200 is electrically connected to a host computer (not graphically illustrated) through a cable 260.
FIGS. 3A and 3B are diagrams illustrating a method of detecting coordinates in the touchscreen panel 200. According to the touchscreen panel 200 having the above-described configuration, voltage is applied alternately in the X-axis and the Y-axis directions with electrodes 241, 242, 243, and 244 provided at the four side ends of the transparent conductive film 240 as illustrated in FIG. 3A. In response to the transparent conductive film 230 and the transparent conductive film 240 coming into contact with each other at contact point (position) A, an electric potential Va is detected through the transparent conductive film 230, thereby detecting an X-axis coordinate position and a Y-axis coordinate position as illustrated in FIG. 3B.